Synthesis of Higher Alcohols from Syngas over Alkali Promoted K-Co-Mo Catalysts Supported on Multi-walled Carbon Nanotubes

A series of carbon nanotubes-supported K-Co-Mo catalysts were prepared by a sol-gel method combined with incipient wetness impregnation. The catalyst structures were characterized by X-ray diffraction, N2 adsorption-desorption, transmission electron microscopy and H2-TPD, and its catalytic performance toward the synthesis of higher alcohols from syngas was investigated. The as-prepared catalyst particles had a low crystallization degree and high dispersion on the outer and inner surface of CNTs. The uniform mesoporous structure of CNTs increased the diffusion rate of reactants and products, thus promoting the reaction conversion. Furthermore, the incorporation of CNTs support led to a high capability of hydrogen absorption and spillover and promoted the formation of alkyl group, which served as the key intermediate for the alcohol formation and carbon chain growth. Benefiting from these characteristics, the CNTs supported Mo-based catalyst showed the excellent catalytic performance for the higher alcohols synthesis as compared to the unsupported catalyst and activated carbon supported catalyst.

Effects of Activation Atmospheres on Structure and Activity of Mo-based Catalyst for Synthesis of Higher Alcohols

Activated carbon supported Mo-based catalysts were prepared and reduced under different activation atmospheres, including pure H2, syngas （H2/CO=2/1）, and pure CO. The cat- alysts structures were characterized by X-ray diffraction , X-ray absorption fine structure, and in situ diffuse reflectance infrared Fourier transform spectroscopy. The catalytic per- formance for the higher alcohol synthesis from syngas was tested. The pure H2 treatment showed a high reduction capacity. The presence of a large amount of metallic CoO and low valence state Mo^φ＋ （0〈φ〈2） on the surface suggested a super activity for the CO dissoci- ation and hydrogenation, which promoted hydrocarbons formation and reduced the alcohol selectivity. In contrast, the pure CO-reduced catalyst had a low reduction degree. The Mo and Co species at the catalyst mainly existed in the form of Mo^4＋ and Co^2＋. The syngas- reduced catalyst showed the highest activity and selectivity for the higher alcohols synthesis. We suggest that the syngas treatment had an appropriate reduction capacity that is between those of pure H2 and pure CO and led to the coexistence of multivalent Co species as well as the enrichment of Mo~＋ on the catalyst＇s surface. The synergistic effects between these active species provided a better cooperativity and equilibrium between the CO dissociation, hydrogenation and CO insertion and thus contributed beneficially to the formation of higher alcohols.

Effect of elemental molar ratio on the synthesis of higher alcohols over Co-promoted alkali-modified Mo_2C catalysts supported on CNTs

A series of molybdenum carbide catalysts promoted by potassium and cobalt,supported on carbon nanotubes（CNTs） were prepared by carbothermal hydrogen reduction method using CNTs as a carbon precursor.Firstly,molybdenum and cobalt were loaded by co-precipitation method,and then potassium and additional molybdenum were impregnated to previous resultant.Different Mo/Co and K/Co molar ratio were used in catalyst synthesis.All the catalysts were characterized by ICP,BET,TEM,TPR,XRD and XPS,and the catalysts performances for higher alcohols synthesis（HAS） were investigated in a fixed-bed micro-reactor.The maximum selectivity to higher alcohols（C2＋OH） was obtained at Mo/Co and K/Mo molar ratios of 1.66 and 0.6,respectively.XRD results confirmed the formation of K-Mo-C site and Co3Mo3 C phase that might play important role in producing C2＋OH.

Cold plasma-activated Cu-Co catalysts with CN vacancies for enhancing CO_(2)electroreduction to low-carbon alcohol

Electrocatalytic CO_(2)reduction reaction to low-carbon alcohol is a challenging task,especially high selectivity for ethanol,which is mainly limited by the regulation of reaction intermediates and subsequent C–C coupling.A Cu-Co bimetallic catalyst with CN vacancies is successfully developed by H_(2)cold plasma toward a high-efficiency CO_(2)RR into low-carbon alcohol.The Cu-Co PBA-V_(CN)(Prussian blue analogues with CN vacancies)electrocatalyst yields methanol and ethanol as major products with a total low-carbon alcohol FE of 83.8%(methanol:39.2%,ethanol:44.6%)at-0.9 V vs.RHE,excellent durability(100 h)and a small onset potential of-0.21 V.ATR-SEIRAS(attenuated total internal reflection surface enhanced infrared absorption spectroscopy)and DFT(density functional theory)reveal that the steric hindrance of V_(CN)can enhance the CO generation from*COOH,and the C–C coupling can also be increased by CO spillover on uniformly dispersed Cu atoms.This work provides a strategy for the design and preparation of electrocatalysts for CO_(2)RR into low-carbon alcohol products and highlights the impact of catalyst steric hindrance to catalytic performance.

Higher alcohol synthesis over Cu-Fe composite oxides with high selectivity to C_(2+)OH

Cu-Fe composite oxides were prepared by co-precipitation method and tested for higher alcohol synthesis from syngas. The selectivity to C2＋OH and C6＋OH in alcohol distribution was very high while the methane product fraction in hydrocarbon distribution was rather low, demonstrating a promising potential in higher alcohols synthesis from syngas. The distribution of alcohols and hydrocarbons approximately obeyed Anderson-Schulz-Flory distribution with similar chain growth probability, indicating alcohols and hydrocarbons derived from the same intermediates. The effects of Cu/Fe molar ratio, reaction temperature and gas hourly space velocity （GHSV） on catalytic performance were studied in detail. The sample with a Cu/Fe molar ratio of 10/1 exhibited the best catalytic performance. Higher reaction temperature accelerated water-gas-shift reaction and led to lower total alcohols selectivity. GHSV showed great effect on catalytic performance and higher GHSV increased the total alcohol selectivity, indicating there existed visible dehydration reaction of alcohol into hydrocarbon.

Cu-Co bi-metal catalyst prepared by perovskite CuO/LaCoO_3 used for higher alcohol synthesis from syngas

Cu-Co bi-metal catalysts derived from CuO/LaCoO3 perovskite structure were prepared by one-step citrate complexing method, and the structure evolution reaction from CuO/LaCoO3 to Cu-Co2C/La202CO3 under 1-12 pretreatment was investigated by techniques of XRD, TPR and TEM. The results suggest that a much higher dispersion of copper significantly enhanced the reduction of cobalt, and a stronger interaction between copper and cobalt ions in LaCoO3 particles led to the formation of bi-metallic Cu-Co particles in the reduced catalysts and the enrichment of Co on the surface of bimetallic particles. The prepared catalysts were highly active and selective for the alcohol synthesis from syngas due to the presence of copper-modified C02C species.

Nanosheet-structured K–Co–MoS_2 catalyst for the higher alcohol synthesis from syngas: Synthesis and activation

The nanosheets structured K–Co–MoS_2 catalyst was prepared through a one-step hydrothermal synthesis combined with the wetness impregnation. The fresh catalyst has a high dispersion of Co–Mo–S active phase and no Co_9S_8 is found. The pure H_2 activated catalyst shows a higher intrinsic activity, especially the C_(2+) OH selectivity for the higher alcohol synthesis compared to the one activated by 5% H_2/N_2 atmosphere. The reason is attributed to that the pure H_2 activation more effectively suppresses the formation of Co_9S_8 and stabilizes the Co–Mo–S active phase during the reaction due to the formation of SH species.

Synthesis and Diffuse Reflectance Spectrum of Open－framework Cobalt Phosphate DAF－2 From Alcoholic System

ＳｙｎｔｈｅｓｉｓａｎｄＤｉｆｆｕｓｅＲｅｆｌｅｃｔａｎｃｅＳｐｅｃｔｒｕｍｏｆＯｐｅｎ－ｆｒａｍｅｗｏｒｋＣｏｂａｌｔＰｈｏｓｐｈａｔｅＤＡＦ－２ＦｒｏｍＡｌｃｏｈｏｌｉｃＳｙｓｔｅｍＹＵＪｉ－ｈｏｎｇ；ＣＨＥＮＪｉｅ－ｓｈｅｎｇａｎｄＸＵＲｕ－ｒ...

On the role of cobalt carbidization in higher alcohol synthesis over hydrotalcite-based Co-Cu catalysts

Co-Cu-based catalysts are widely applied in higher alcohol synthesis (HAS) from synthesis gas. Although the nature of the active sites is still not fully understood, the formation of Co2C under HAS conditions seems to play a major role. A CO pretreatment procedure was developed allowing a systematic investigation of the influence of cobalt carbidization on the structural properties and catalytic performance of the catalysts. By exposing the catalyst to a CO-containing atmosphere prior to HAS, Co enrichment of the catalyst surface occurred followed by carbide formation. This surface modification decreased the formation of hydrocarbons and enhanced the formation of C2+OH. The catalyst pretreated with CO at 20 bar achieved the highest selectivity to ethanol and the lowest hydrocarbon selectivity.

Practical synthesis allenyl and homopropargyl alcohol through Cp_2TiCl_2 -Mg with propargyl alcohol derivatives

Reaction of Cp2TiCl2-Mg synthetic equivalent of practical Ti(II) reagent with propargyl alcohol derivatives affords allenyl titanium compounds in good yields.thus, providing an efficient and practical methods for synthesis of both allenyl and homopropargyl alcohols by the successive treatment with aldehydes and ketones.

mi R-192-5p regulates lipid synthesis in non-alcoholic fatty liver disease through SCD-1

AIM To evaluate the levels of mi R-192-5 p in non-alcoholic fatty liver disease(NAFLD) models and demonstrate the role of mi R-192-5 p in lipid accumulation. METHODS Thirty Sprague Dawley rats were randomly divided into three groups, which were given a standard diet, a high-fat diet(HFD), and an HFD with injection of liraglutide. At the end of 16 weeks, hepatic mi R-192-5 p and stearoyl-Co A desaturase 1(SCD-1) levels were measured. Mi R-192-5 p mimic and inhibitor and SCD-1 si RNA were transfected into Huh7 cells exposed to palmitic acid(PA). Lipid accumulation was evaluated by oil red O staining and triglyceride assays. Direct interaction was validated by dual-luciferase reporter gene assays.RESULTS The HFD rats showed a 0.46-fold decrease and a 3.5-fold increase in hepatic mi R-192-5 p and SCD-1 protein levels compared with controls, respectively, which could be reversed after disease remission by liraglutide injection(P < 0.01). The Huh7 cells exposed to PA also showed down-regulation and up-regulation of mi R-192-5 p and SCD-1 protein levels, respectively(P < 0.01). Transfection with mi R-192-5 p mimic and inhibitor in Huh7 cells induced dramatic repression and promotion of SCD-1 protein levels, respectively(P < 0.01). Luciferase activity was suppressed and enhanced by mi R-192-5 p mimic and inhibitor, respectively, in wild-type SCD-1(P < 0.01) but not in mutant SCD-1. Mi R-192-5 p overexpression reduced lipid accumulation significantly in PA-treated Huh7 cells, and SCD-1 si RNA transfection abrogated the lipid deposition aggravated by mi R-192-5 p inhibitor(P < 0.01).CONCLUSION This study demonstrates that mi R-192-5 p has a negative regulatory role in lipid synthesis, which is mediated through its direct regulation of SCD-1.

Enantioselective Synthesis of Chiral 1-Ferrocenyl Alcohol via CBS-Reduction

Reduction of prochiral ferrocenyl ketones 2a-e in the presence of 10 mol% of chiral beta -amino alcohols 4a-b provides 1-ferrocenyl alcohols 1a-e in high yields (> 85%) with high optically purity (e.e. up to 96%).

Synthesis of Cytotoxic Sinapyl Alcohol Derivatives fromLigularia nelumbifolia

Total synthesis of two cytotoxic natural products, nelumol A (1) and nelumal A (2), were carried out by two different paths. 4-O-Benzyl substitute analogues 26 and 27, as well as the 4-O-(2-methyl-butenyl) derivatives 29 and 30 were also synthesized for a SAR investigation. 1 and 2 were also measured on different tumor cell line.

Bifunctionality of Cu/ZnO catalysts for alcohol-assisted low-temperature methanol synthesis from syngas:Effect of copper content

Alcohol-assisted low-temperature methanol synthesis was conducted over Cu/ZnO;catalysts while varying the copper content（X）. Unlike conventional methanol synthesis, ethanol acted as both solvent and reaction intermediate in this reaction, creating a different reaction pathway. The formation of crystalline phases and characteristic morphology of the co-precipitated precursors during the co-precipitation step were important factors in obtaining an efficient Cu/ZnO catalyst with a high dispersion of metallic copper,which is one of the main active sites for methanol synthesis. The acidic properties of the Cu/ZnO catalyst were also revealed as important factors, since alcohol esterification is considered the rate-limiting step in alcohol-assisted low-temperature methanol synthesis. As a consequence, bifunctionality of the Cu/ZnO catalyst such as metallic copper and acidic properties was required for this reaction. In this respect, the copper content（X） strongly affected the catalytic activity of the Cu/ZnO;catalysts, and accordingly, the Cu/ZnO;.5 catalyst with a high copper dispersion and sufficient acid sites exhibited the best catalytic performance in this reaction.

Polystyrene-supported Selenides and Selenoxide: Versatile Routes to Synthesize Allylic Alcohols

Several polystyrene-supported selenides and selenoxide have been prepared firstly. These novel reagents were treated with LDA to produce selenium stabilized carbanions, which reacted with aldehydes and alkyl halides, followed by selenoxide syn-elimination and [2,3] sigmatropic rearrangement respectively to give Z-allylic alcohols stereoselectively.

First Total Synthesis of (-)-4-O-(6'-hydroxy-7'(9')-dehydro-6',7'-dihydrogeranyl)-coniferyl Alcohol

The reduction of 2,3-epoxy alcohol, prepared from the Sharpless asymmetric epoxidation, with the system of Ph3P, iodine, iwhdazole, 2,6-lutidine and water in Et2O/CH3CN,gives a chiral secondary allylic alcohol in 94% yield and 92% e.e.. Using this reaction as the key step, we synthesized (-)-coniferyl alcohol derivative 1 steding from the geraniol through nine steps in an overall yield of 39%.

Synthesis of tetrahedrally coordinated CoO for higher alcohol synthesis directly from syngas

Higher alcohol synthesis directly from syngas is highly desirable as one of the efficient non-petroleum energy conversion routes.Co0–Co^(O)catalysts showed great potential for this reaction,but the alcohol selectivity still needs to be improved and the crystal structure effect of Co^(O)on catalytic behaviors lacks investigation.Here,a series of tetrahedrally coordinated Co^(O)polymorphs were prepared by a thermal decomposition method,which consisted of wurtzite CoO and zinc blende CoO with varied contents.After diluting with SiO_(2),the catalyst showed excellent performance for higher alcohol synthesis with ROH selectivity of 45.8%and higher alcohol distribution of 84.1 wt%under the CO conversion of 38.0%.With increasing the content of wurtzite CoO,the Co^(0)/Co^(2+)ratio gradually increased in the spent catalysts,while the proportion of highly active hexagonal close packed cobalt in Co^(0)decreased,leading to first decreased then increased CO conversion.Moreover,the higher content of zinc blende CoO in fresh catalyst facilitated the retention of more Co^(2+)sites in spent catalysts,promoting the ROH selectivity but slightly decreasing the distribution of higher alcohols.The catalyst with 40%wurtzite CoO obtained the optimal performance with a space time yield toward higher alcohols of 7.9 mmol·gcat^(-1)·h^(-1).